Drilling apparatus with down hole motor

ABSTRACT

The apparatus comprises a rotary drill rod comprising an elongated pipe having a longitudinally extending bore therethrough and a percussive bit at the distal end thereof. Means define an abutment which is relatively transverse the bore adjacent the bit and operatively connected with the bit to receive and transmit hammer blows into the working face of the bit. The apparatus also comprises drive means that include a piston-like member which is retractably inserted in the bore in slidable engagement with the wall thereof and has a fluid operated hammer mechanism thereon, the hammer of which is reciprocable between the member and the abutment to apply the blows to the abutment. In addition, there are fluid transmission means for operating the hammer mechanism including means for passing fluid through the piston-like member and means for exhausting the fluid into the region adjacent the working face of the bit after the mechanism has operated. There are also means on the rod whereby the exhaust fluid can discharge from said region toward the proximal end of the pipe on the opposite side of the pipe from the piston-like member; and means on the piston-like member for generating a pressure differential across the drive means longitudinally of the bore to maintain the mechanism in operative relationship to the abutment during the application of the blows.

[ Dec. 17, 1974 United States Patent [191 Sweeney [57] ABSTRACT The apparatus comprises a rotary drill rod com DRILLING APPARATUS WITH DOWN HOLE MOTOR prising an elongated pipe having a longitudinally extending [75] Inventor: Gerald Sweeney Federal bore therethrough and a percussive bit at the distal Wash.

end thereof. Means define an abutment WhlCh IS rela- Assignee? g Tiel'la, -9 Puyallup, Washtively transverse the bore adjacent the bit and opera- Filed: Aug 23, 1972 tively connected with the bit to receive and transmit App]. No.: 283,208

hammer blows into the working face of the bit. The apparatus also comprises drive means that include a piston-like member which is retractably inserted in the 52 US. 175/92, 173/73, 173/80, bore in Slidable engagement with the Wall hereof and has a fluid operated hammer mechanism thereon, the

175/257, 175/296 E21b 1/06, E2lb 9/20 Inn hammer of which is reciprocable between the member and the abutment to apply the blows to the abutment.

[58] Field of Search....... 175/58, 92, 236, 257, 105

In addition, there are fluid transmission means for operating the hammer mechanism including means for passing fluid through the piston-like member and means for exhausting the fluid into the region adjacent 57 61 05%39 12l/2 vl zmn 77117 11 l S m T m N m E .m d a A m u t .10.. C un S 5 %E n m h CT ewefl nA m lt N m m mm SfiFMMH eD E94 T245666 l99ww lu l w u m 196377 7303 0 7530 1.] 14 2892 6 23. B. 2233 the working face of the bit after the mechanism has operated. There are also means on the rod whereby the exhaust fluid can discharge from said region toward the proximal end of the pipe on the opposite side of the pipe from the piston-like member; and means on the piston-like member for generating a pressure jdifferential across the drive means longitudinally of the bore to maintain the mechanism in operative relal/l972 Cobbs..... 8/1972 tionship to the abutment during the application of the Klemm............

blows.

Primary ExaminrJames A. Leppink Attorney, Agent, or Firm-Christenson, OConnor, Garrison & Havelka 32 Claims, 5 Drawing Figures n rllfflfllllllflrllllrlIIIII III l ll E I A 3.854.539 SHEET 2 0F 2 I o a D I I H .IH NIH MIIIWEH ll 4 NIL w 0 4 0 Mm a x v a, w 7 z w a M M w M a 1 i| I 1 I A 4m: 1 I n? v H w 7!! PATENTEL; LEE 1 7 I974 V $8 I K DRILLING APPARATUS WITH DOWN .HQLILMQIQRA. -N.

THE INVENTION IN GENERAL According to the invention, the apparatus comprises a rotary drill rod comprising an elongated pipe having a longitudinally extending bore therethrough and a percussive bit at the distal end thereof. Means define an abutment which is relatively transverse the bore adjacent the bit and operatively connected with the bit to receive and transmit hammer blows into the working face of the bit. The apparatus also comprises drive means that include a piston-like member which is retractably inserted in the bore in slidable engagement with the wall thereof and has a fluid operated hammer mechanism thereon, the hammerof which is reciprocable between the member and the abutment to apply the blows'to the abutment. In addition, there are fluid transmission means for operating the hammer mechanism including means for passing fluid through the piston-like member and means for exhausting the fluid into the region adjacent the working face of the bit after the mechanism has operated. There are also means on the rod whereby the exhaust fluid can discharge from said region towarad the proximal end of the pipe on the opposite side of the pipe from the piston-like member; and means on the piston-like member for generating a pressure differential across the drive means longitudinally of the bore to maintain the mechanism in operative relationship to the abutment during the application of the blows.

The bit may have a greater diameter than the pipe, and the pipe may form the inner periphery of an annulus which is disposed between the pipe and the wall of the excavated hole, to pass the exhausted fluid therethrough. Also, the pipe may be rotated during the drilling operation, and the bit may be engaged on the distal end of the pipe to rotate in conjunction therewith. In fact, the bit may be rigidly connected to the distal end of the pipe.

Where the bit has a greater diameter than the pipe, the fluid exhaust means may be operative to exhaust the fluid through the body of the bit, and the outer periphery of the bit may be adapted to enable the exhausted fluid to discharge thereacross into an annulus formed by the pipe and the wall of the excavated hole.

The abutment may be disposed on the pipe.

The drive means may also include an anvil relatively reciprocably interposed in the bore between the hammer and the abutment to receive and transmit the blows to the abutment. Also, the bit may be annular, and the apparatus may further comprise excavation means on the distal end of the anvil adjacent the inner peripheral opening of the bit. The anvil may be engageable with the abutment and the excavation means may be interposed between the abutment and the mouth of the opening. Also, the excavation means may be re cessed and the recess may be interposed between the anvil and the mouth of the opening to receive formation material through the opening. For example, the anvil may have a core barrel thereon.

The excavation means may be detachablyconnected to the anvil. Also, the excavation means maybe axially and/or rotationally displaceable in relation to the anvil.

Moreover, the excavation means may be relatively rotatably engaged with the bore of the rod.

The anvil may define a passage for the fluid and the fluid exhaust means may be operative to exhaust the fluid through the anvil passage. Also, the excavation means may define a continued passage for the fluid with the rod, and the fluid exhaust means may be operative to exhaust the fluid through the continued passage. Moreover, the bit may define a port for the fluid through the body thereof and the fluid exhaust means may be operative to exhaust the fluid through the port.

The anvil may be operably connected with the piston-like member and adapted to be retracted from the bore with the member. Also, the anvil may be slidably engaged with the wall of the bore.

The proximal end portion of the bore may be operatively fluid pressurized, and the pressure differential generating means may be operative to cause a pressure drop across the drive means in the direction of the distal end of the bore. The piston-like member may define a passage for the fluid and the passage may open into the bore of the rod at the proximal end of the member. Also, the piston-like member may define a passage for the fluid which has a throttle valve therein that is biased to close the passage to fluid flow until a predetermined fluid pressure is achieved at the proximal end thereof.

The hammer mechanism may be interposed between the piston-like member and the distal end of the bore, in spaced relationship to the abutment and the wall of the bore.

The apparatus may further comprise attachment means on the proximal end of the piston-like member for releasable engagement by a wire line retriever or the like.

The abutment may take the form of an anvil relatively reciprocably interposed in the bore between the hammer and the face of the bit to receive and transmit the blows to the bit, and the fluid exhaust means may be operative to exhaust the fluid through the anvil. Also, the anvil may be disposed in the pipe and slidably engaged with the wall of the bore, between the hammer and the bit.

BRIEF DESCRIPTION OF THE DRAWINGS These features will be better understood by reference to the accompanying drawings wherein:

FIG. I is a part longitudinal cross-sectional view of one of my presently preferred embodiments of the invention, as it is seen in use for a down-the-hole core drilling operation, and with the hammer mechanism in the bottomed condition thereof;

FIG. 2 is another such view as the hammer mechanism is in the upstroke thereof;

FIG. 3 is a transverse cross-sectional view along the line 3-3 of FIG. 1;

FIG. 4 is another part longitudinal cross-sectional view when the drive means has been retracted from the drill rod; and

FIG. 5 is a part perspective view of the bit in the drill rod.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, it will be seen that the drill rod comprises an elongated, fluid pressurized pipe 2,

employed which is assembled from equal-diameter sections that are perhaps feet in length and threaded and flushcoupled to one another as illustrated. With the exception of the interior of the bottommost or distal end section 2' of the pipe, the sections are otherwise similar to one another, and are added to and subtracted from the pipe as is necessary during the drilling operation. The distal end section 2' differs, however, in that it has a stepped or counterbored interior configuration which forms an inner peripheral shoulder 3 at a point near the top thereof. The shoulder serves as an abutment for the drive means 4, which is retractable from the rod, as shall be explained; and the which includes a standard, fluid-operated down-the-hole hammer mechanism 5.

The pipe is pressurized and driven by a conventional drilling mechanism, such as that shown in [1.8. Pat. No. 3,391,543, and is typically driven at slow speeds such as 10 RPM, that is, at speeds simply sufficient to index the percussion bit 7 seen at the bottom or distal end of the pipe. The bit.7 is annular in configuration, and has an interiorly threaded collar 8 at the upper end thereof, that flush-couples to the distal end section 2' of the pipe. Below the collar, however, the bit is flared radially outwardly and forms an enlarged head 10 which terminates with a flat-faced annulus 12 at the working end thereof. The annulus has sets of button-like percussion points 14 seated in raised condition thereon, which are spaced apart in angularly spaced, clockwise, convolutional lines that are symmetrically arranged about the axis of the bit. See FIG. 5. In addition, the endmost points 14 on each line, are seated in the head so as to project slightly inside and outside of the inner and outer peripheries of the annulus, respectively. As a consequence, when the rod is rotated and hammeredinto an earth formation 16, the bit excavates an annular recess the outside diameter of which is not only greater than the outside diameter of the pipe itself, but also greater than the outside diameter of the flared head 10 of the bit. Likewise, the core 18 of earth material which is captured within the end of the rod, has an outside diameter of slightly lesser dimension than the inside diameter of the head of the bit.

Otherwise, the bit has a stepped or counterbored interior configuration forming an annular shoulder 20 inside of and about the bottom end of the collar 8. The interior of the bit also has another annular shoulder 22 therebelow, which is of lesser inside and outside dimensions than the shoulder 20, by virtue of there being an inwardly chamfered surface 24 at the bottom of the cylindrical socket 26 separating the two shoulders. The lower shoulder 22 and the socket 26 form a seat for a core barreling tube 40 on the drive means, as shall be explained; whereas the upper shoulder 20 has an annular groove 30 recessed therein, from which a series of symmetrically angularly spaced ports 32 open through the body of the head 10 to the working face 12 of the bit, between the points 14 thereon. The ports are also canted to the axis of the head, and are so angled into 'the shoulder that they open into the socket 26.

During the drilling operation, the compressed fluid is intermittently discharged to the ports 32 to flush the removed earth material back through the clearance 34 between the pipe 2 and the wall of the excavation. The fluid reaches the ports through a series of passages 36 which are formed within the drive means and the distal end section 2 of the pipe, as shall be explained more fully hereinafter.

The drive means 4 also includes an annular anvil 38 which is slidably engageable in the upper, thinner walled portion of the distal end section 2, and sized to seat on the shoulder 3. The core barreling tube 40 is slidably engageable in the bore 42 of the lower, thicker walled portion of the section 2', and suspended from the anvil to seat relatively rotatably within the socket 26 of the bit. The tube is equipped with a bushed, ball bearing mounted swivel head 44 on the upper end thereof, and the bushing 46 of the head is slidably engaged on, but rotationally keyed to a flanged swivel pin 48, which is fastened upright to the underside of the anvii. Moreover, the keyway 50 for the bushing, and the length of the bushing, are sized in relation to the pin, to allow for play between the tube and the anvil, axially thereof; and a coiled spring 52 is interposed about the bushing 46, between the head and the underside of the anvil, to bias the tube in the downward direction, toward the flange 48' of the pin. Thus, when the drive means 4 is lowered into the bore of the pipe 2, the tube 40 is urged to seat within the bit, both by the spring 52 and by the force of gravity; yet it is also free to undergo displacement in relation to the anvil, where there is earth material lodged within the bit. The earth material may be dislodged, however, either by the piston, or by the fluid discharge, or by both, as shall be explained hereinafter.

In addition to being adapted to mate with the bit, the forward end portion 40 of the tube 40 is also adapted to lift or separate the core 18 from the earth formation when the drive means 4 is retracted from the rod. The tube 40 is formed in two threaded and flushedcoupled parts, the more forward 40' of which is chamfered at the end, so as to mate with the chamfered socket 26 of the bit, and form an essentially air tight joint therebetween. The more forward portion 40 also has an upwardly and outwardly tapered surface 54 formed between the cylindrical mouth 56 and the threaded collar 58 of the same; and when the two parts of the tube are assembled, a tapered wedge-like annular core lifter 60 is inserted within the more forward portion, to perform the core lifting and separating function in conventional fashion.

The outer cylindrical surface 62 of the anvil is closely machined to form a fluid seal with the bore of the pipe. Above the surface, however, the anvil is swaged inwardly and provided with a filleted shoulder 64 thereabout, from which a nipple-like shank or embossment 66 is upstanding on the axis of the anvil, and equipped with a wide circumferential groove 68 thereabout. The bore 70 of the anvil is counterbored from above and below, and the upper counterbore 72 of the same is adapted to interengage with the hammer mechanism, as shall be explained, whereas the lower counterbore 74 provides a socket for the swivel pin 48, which is secured in the socket by means of a dowel 76.

The hammer mechanism 5 is a modified version of a standard down-the-hole air hammer mechanism, comprising an outer tubular casing 78 having a pipe hammer 80 reciprocably engaged about a stationary control rod 82 therein. The control rod 82 is ported and infrastructured to enable the compressedfluid to reciprocate the hammer in known manner, and alternately to exhaust through porting 84 in the distal end 86 of the control rod. The fluid enters the control rod through a port or ports in a spear-headed, piston-like cap 88 which is threaded onto the upper end of the casing and adapted to slidably engage with the wall of the bore of the pipe 2, as illustrated. The ports 90 are equipped with spring-loaded throttle valves 92 that operate to produce a pressure drop between the upper and lower sides of the drive means, so that the fluid can assist in seating the anvil on the shoulder 3 of the pipe. The anvil coupled to the hammer mechanism by telescopically engaging a threaded, two-part, inner ribbed collar 98 about the embossment 66 of the anvil 38, and flushcoupling the collar to the distal end of the casing 78, the inner circumferential rib 100 of the collar, meanwhile interengaging in the groove 68 of the embossment. The drive means is retracted from the rod by an overhead hoist, such as a standard wire-line retriever, the dogs 96 of which are engaged about the spearhead 94 of the cap.

During the drilling operation, the hammer 80 interfaces with the annulus 102 at the upper end of the anvil, and applies intermittent blows to the anvil, as the pipe 2 is rotated thereabout. Thus, the bit is continually advanced in the axial direction by the percussive effect of the hammer, and at the same time, is continually rotated by the rod pipe, so that the points 14 of the bit are reindexed with respect to the face of the excavation,

each time that the hammer strikes. Moreover, due to the telescoping relationship between the tube 40 and the pipe, and the relatively reciprocable, swiveled relationship between the tube and the anvil, the tube remains substantially stationary with respect to the pipe, as the pipe is rotated and advanced into the formation.

During the drilling operation, moreover, the exhaust porting 84 in the control rod is placed in communication with the passages 36, so as to exhaust the fluid about the bit. As seen, the distal end portion 86 of the control rod is slidably inserted in the bore 72 of the anvil; and in the bore, there is a series of symmetrically angularly spaced and outwardly slanted ports 104, which open to the underside of the anvil, opposite the chamber 106 which is formed between the head 44 of the tube and the anvil. From there, the fluid enters a series of symmetrically angularly spaced flutes 108 in the bore 42 of the pipe, which commence below the level of the shoulder 3, and terminate in the distal end of the pipe, to communicate with the groove 30 and the ports 32 in the bit. In the engaged and socketed condition of the tube 40, the open sides of the flutes are closed by the main body of the tube, and the socket 26 is occupied by the forward portion 40' thereof, so that the fluid canescape only through the ports 32. Until the tube is socketed in the bit, however, a portion of the fluid will discharge through the axial opening of the bit, so as to assist in flushing out any accumulated debris which would otherwise prevent the tube from seating in the socket of the bit.

Moreover, in such a case, the spring 52 will be compressed by the tube to the point where the bushing 46 of the swivel head engages the face of the anvil; and thereafter, when the hammer 80 is applied to the anvil, the force of the hammer will operate on the tube only. until the anvil re-engages the shoulder 3 of the rod. Thus, the operator can be assured that the tube will be properly seated before the drilling operation is begun.

In the seating process, moreover, a passage 110 through the pin 48, assures that the tube 40 is also pressurized, so that the debris can move only in the direction outward through the clearance 34.

Of course, as drilling progresses, more and more sections are added to the drill pipe 2. If necessary or desired, the tube can be changed at the same time to account for wear of the inner points of the bit; or the bit can be changed; or both can be changed.

For overhead or sidewall drilling, the fluid may also be employed as a means of seating the drive means; as for example, where the drive means is run into the rod at a pressure below that at which the valves 92 open, and then the pressure is raised to open the valves and commence drilling.

Where it is desired to drill for a period without coring, a plug-like bit can be substituted for the core barreling tube, and interengaged either with the pipe or with the annular bit, to rotate conjointly with the same.

I claim:

1. In combination, a rotary drill rod comprising an elongated pipe having a longitudinally extending bore therethrough and a percussive bit at the distal end thereof, means defining an abutment relatively transverse the bore adjacent the bit and operatively connected with the bit to receive and transmit hammer blows into the working face of the bit, drive means including a piston-like member retractably inserted in the bore in slidable engagement with the wall thereof and having a fluid operated hammer mechanism thereon, the hammer of which is reciprocable between the member and the abutment to apply the blows to the abutment, fluid transmission means for operating the hammer mechanism including means for passing fluid through the piston-like member and means for exhausting the fluid into the region adjacent the working face of the bit after the mechanism has operated, means on the rod whereby the exhausted fluid can discharge from said region toward the proximal end of the pipe on the opposite side of the pipe from the piston-like member, and means on the piston-like member for generating a pressure differential across the drive means longitudinally of the bore to maintain the mechanism in operative relationship to the abutment during the application of the blows.

2. The combination according to claim 1 wherein the abutment is disposed on the pipe.

3. The combination according to claim I wherein the proximal end portion of the bore is operatively fluid pressurized, and the pressure differential generating means is operative to cause a pressure drop across the drive means in the direction of the distal end of the bore.

4. The combination according to claim 1 wherein the piston-like member defines a passage for the fluid and the passage opens into the bore of the rod at the proximal end of the member.

5. The combination according to claim 1 wherein the piston-like member defines a passage for the fluid and the passage has a throttle valve therein which is biased to close the passage to fluid flowuntil a predetermined fluid pressure is achieved at the proximal end thereof.

6. The combination according to claim I wherein the hammer mechanism is interposed between the pistonlike member and the distal end of the bore, in spaced relationship to the abutment and the wall of the bore.

7. The combination according to claim 1 further comprising attachment means on the proximal end of the piston-like member for releaseable engagement by a wire line retriever or the like.

8. The combination according to claim 1 wherein the I 11. The combination according to claim 8 wherein the bit is annular, the fluid exhaust means is operative to exhaust the fluid through the body of the bit, and the outer periphery of the bit is adapted to enable the exhausted fluid to discharge thereacross into an annulus formed by the pipe and the wall of the excavated hole.

12. The combination according to claim 1 wherein the bit is annular and the abutment takes the form of an anvil relatively reciprocably interposed in the bore between the hammer and the face of the bit to receive and transmit the blows to the bit, and wherein the fluid exhaust means is operative to exhaust the fluid through the anvil.

13. The combination according to claim 12 wherein the anvil is disposed in the pipe and slidably engaged with the wall of the bore, between the hammer and the bit.

14. The combination according to claim 1 wherein the drive means also includes an anvil relatively reciprocably interposed in the bore between the hammer and the abutment to receive and transmit the blows to the abutment.

15. The combination according to claim 14 wherein the bit is annular, and further comprising excavation means on the distal end of the anvil adjacent the inner peripheral opening of the bit.

16. The combination according to claim 15 wherein the anvil is engageable with the abutment and the excavation means is interposed between the abutment and the mouth of the opening.

17. The combination according to claim 15 wherein the excavation means is recessed and the recess is interposed between the anvil and the mouth of the opening to receive formation material through the opening.

18. The combination according to claim 15 wherein the anvil has a core barrel thereon.

19. The combination according to claim 15 wherein the excavation means is detachably connected to the anvil.

20. The combination accordingto claim 15 wherein the excavation means is axially andfor rotationally displaceable in relation to the anvil.

21. The combination according to claim 15 wherein the excavation means is relatively rotatably engaged with the bore of the rod.

22. The combination according to claim 15 wherein the anvil defines a passage for the fluid and the fluid exhaust means is operative to exhaust the fluid through the anvil passage.

23. The combination according to claim 22 wherein the excavation means defines a continued passage for the fluid with the rod, and the fluid exhaust means is operative to exhaust the fluid through the continued passage.

24. The combination according to claim 23 wherein the bit defines a port for the fluid through the body thereof and the fluid exhaust means is operative to exhaust the fluid through the port.

25. The combination according to claim 14 wherein the anvil is operably connected with the piston-like member and adapted to be retracted from the bore with the member.

26. The combination according to claim 25 wherein the anvil is slidably engaged with the wall of the bore.

27. Apparatus for extracting material from an earth formation, comprising a rotary drill pipe having an annular bit on the distal end thereof which is adapted to be hammered into the formation as the pipe is rotated theretoward, a core barreling tube retractably inserted in the pipe, and means for transmitting hammer blows to the bit while the bit is rotated, and retracting the tube from the pipe when the bit is idle, including an anvil retractably seated in the pipe, to be used as an abutment for a reciprocable hammer mechanism which is employed to apply the blows to the pipe, said anvil being engaged with the pipe to transmit the blows to the bit through the pipe, and operably connected to the tube so that it can retract the tube from the pipe when the bit is idle, said bit being oversized and having ports in the body thereof, said hammer being reciprocated with a compressed fluid which is exhausted about the bit to flush the cuttings from the formation around the pipe, and said apparatus further comprising means for exhausting the fluid to the ports of the bit, through the anvil, and thence between the tube and the pipe. 28. The apparatus according to claim 27, wherein the tube is slidably interposed in the pipe between the anvil and the bit, and is relatively rotatably interconnected with the anvil to remain stationary in the pipe as the pipe is rotated.

29. The apparatus according to claim 28, wherein the tube is relatively rotatably engaged with the inner peripheral opening of the bit to prevent the cuttings from escaping between the tube and the pipe.

30. The apparatus according to claim 29, wherein the tube and the pipe are interengaged with one another, to define a passage or passages to the ports of the bit, which operate to discharge the fluid into the inner peripheral opening of the bit until the tube engages with the bit, so that any cuttings therebetween can be flushed away from the area of engagement.

31. The apparatus according to claim 30, wherein the tube is slidably interconnected with the anvil, but yieldably biased in the direction away from the anvil, so that the tube will normally engage the bit, but in the presence of cuttings therebetween, will be retracted against the bias thereon, to be hammered into engagement thereafter, when the hammer mechanism is operated against the anvil.

32. The apparatus according to claim 29, further comprising means for exhausting a portion of the fluid through the tube, to prevent the cuttings from entering the tube. 

1. In combination, a rotary drill rod comprising an elongated pipe having a longitudinally extending bore therethrough and a percussive bit at the distal end Thereof, means defining an abutment relatively transverse the bore adjacent the bit and operatively connected with the bit to receive and transmit hammer blows into the working face of the bit, drive means including a piston-like member retractably inserted in the bore in slidable engagement with the wall thereof and having a fluid operated hammer mechanism thereon, the hammer of which is reciprocable between the member and the abutment to apply the blows to the abutment, fluid transmission means for operating the hammer mechanism including means for passing fluid through the pistonlike member and means for exhausting the fluid into the region adjacent the working face of the bit after the mechanism has operated, means on the rod whereby the exhausted fluid can discharge from said region toward the proximal end of the pipe on the opposite side of the pipe from the piston-like member, and means on the piston-like member for generating a pressure differential across the drive means longitudinally of the bore to maintain the mechanism in operative relationship to the abutment during the application of the blows.
 2. The combination according to claim 1 wherein the abutment is disposed on the pipe.
 3. The combination according to claim 1 wherein the proximal end portion of the bore is operatively fluid pressurized, and the pressure differential generating means is operative to cause a pressure drop across the drive means in the direction of the distal end of the bore.
 4. The combination according to claim 1 wherein the piston-like member defines a passage for the fluid and the passage opens into the bore of the rod at the proximal end of the member.
 5. The combination according to claim 1 wherein the piston-like member defines a passage for the fluid and the passage has a throttle valve therein which is biased to close the passage to fluid flow until a predetermined fluid pressure is achieved at the proximal end thereof.
 6. The combination according to claim 1 wherein the hammer mechanism is interposed between the piston-like member and the distal end of the bore, in spaced relationship to the abutment and the wall of the bore.
 7. The combination according to claim 1 further comprising attachment means on the proximal end of the piston-like member for releaseable engagement by a wire line retriever or the like.
 8. The combination according to claim 1 wherein the bit has a greater diameter than the pipe, and the pipe forms the inner periphery of an annulus which is disposed between the pipe and the wall of the excavated hole, to pass the exhausted fluid therethrough.
 9. The combination according to claim 8 wherein the pipe is rotated during the drilling operation, and the bit is engaged on the distal end of the pipe to rotate in conjunction therewith.
 10. The combination according to claim 9 wherein the bit is rigidly connected to the distal end of the pipe.
 11. The combination according to claim 8 wherein the bit is annular, the fluid exhaust means is operative to exhaust the fluid through the body of the bit, and the outer periphery of the bit is adapted to enable the exhausted fluid to discharge thereacross into an annulus formed by the pipe and the wall of the excavated hole.
 12. The combination according to claim 1 wherein the bit is annular and the abutment takes the form of an anvil relatively reciprocably interposed in the bore between the hammer and the face of the bit to receive and transmit the blows to the bit, and wherein the fluid exhaust means is operative to exhaust the fluid through the anvil.
 13. The combination according to claim 12 wherein the anvil is disposed in the pipe and slidably engaged with the wall of the bore, between the hammer and the bit.
 14. The combination according to claim 1 wherein the drive means also includes an anvil relatively reciprocably interposed in the bore between the hammer and the abutment to receive and transmit the blows to the abutment.
 15. The combination according to claim 14 wherein The bit is annular, and further comprising excavation means on the distal end of the anvil adjacent the inner peripheral opening of the bit.
 16. The combination according to claim 15 wherein the anvil is engageable with the abutment and the excavation means is interposed between the abutment and the mouth of the opening.
 17. The combination according to claim 15 wherein the excavation means is recessed and the recess is interposed between the anvil and the mouth of the opening to receive formation material through the opening.
 18. The combination according to claim 15 wherein the anvil has a core barrel thereon.
 19. The combination according to claim 15 wherein the excavation means is detachably connected to the anvil.
 20. The combination according to claim 15 wherein the excavation means is axially and/or rotationally displaceable in relation to the anvil.
 21. The combination according to claim 15 wherein the excavation means is relatively rotatably engaged with the bore of the rod.
 22. The combination according to claim 15 wherein the anvil defines a passage for the fluid and the fluid exhaust means is operative to exhaust the fluid through the anvil passage.
 23. The combination according to claim 22 wherein the excavation means defines a continued passage for the fluid with the rod, and the fluid exhaust means is operative to exhaust the fluid through the continued passage.
 24. The combination according to claim 23 wherein the bit defines a port for the fluid through the body thereof and the fluid exhaust means is operative to exhaust the fluid through the port.
 25. The combination according to claim 14 wherein the anvil is operably connected with the piston-like member and adapted to be retracted from the bore with the member.
 26. The combination according to claim 25 wherein the anvil is slidably engaged with the wall of the bore.
 27. Apparatus for extracting material from an earth formation, comprising a rotary drill pipe having an annular bit on the distal end thereof which is adapted to be hammered into the formation as the pipe is rotated theretoward, a core barreling tube retractably inserted in the pipe, and means for transmitting hammer blows to the bit while the bit is rotated, and retracting the tube from the pipe when the bit is idle, including an anvil retractably seated in the pipe, to be used as an abutment for a reciprocable hammer mechanism which is employed to apply the blows to the pipe, said anvil being engaged with the pipe to transmit the blows to the bit through the pipe, and operably connected to the tube so that it can retract the tube from the pipe when the bit is idle, said bit being oversized and having ports in the body thereof, said hammer being reciprocated with a compressed fluid which is exhausted about the bit to flush the cuttings from the formation around the pipe, and said apparatus further comprising means for exhausting the fluid to the ports of the bit, through the anvil, and thence between the tube and the pipe.
 28. The apparatus according to claim 27, wherein the tube is slidably interposed in the pipe between the anvil and the bit, and is relatively rotatably interconnected with the anvil to remain stationary in the pipe as the pipe is rotated.
 29. The apparatus according to claim 28, wherein the tube is relatively rotatably engaged with the inner peripheral opening of the bit to prevent the cuttings from escaping between the tube and the pipe.
 30. The apparatus according to claim 29, wherein the tube and the pipe are interengaged with one another, to define a passage or passages to the ports of the bit, which operate to discharge the fluid into the inner peripheral opening of the bit until the tube engages with the bit, so that any cuttings therebetween can be flushed away from the area of engagement.
 31. The apparatus according to claim 30, wherein the tube is slidably interconnected with the anvil, but yieldably biased in the direction away from the anvil, so that the tube will normally engage the bit, but in the presence of cuttings therebetween, will be retracted against the bias thereon, to be hammered into engagement thereafter, when the hammer mechanism is operated against the anvil.
 32. The apparatus according to claim 29, further comprising means for exhausting a portion of the fluid through the tube, to prevent the cuttings from entering the tube. 